1. Field of Invention
This invention relates generally to improvements in toilet flush apparatus and, more particularly, to those improvements which enable, selectively, either a full flush or a partial flush of the water in the flush tank.
2. Description of the Prior Art
In recent years, it has become more and more apparent that our natural resources are not as plentiful as they were once believed to be. It came to be realized that even water, one of our most plentiful of natural resources, was becoming threatened. As a result, efforts began to conserve more natural resources, including water. It also came to be realized that one device, in particular, utilized daily by individuals, namely a toilet, consumes very large amounts of water in its operation. Although a full capacity of the flush tank for a toilet may be necessary in order to dispose of solid wastes, a much smaller quantity of flush water is effective to dispose of liquid wastes. Hence, if a toilet performs a full flush even when disposing of liquid wastes, the consumption of water in the disposal process is unnecessary and excessive. When such usage by an individual is multiplied by the size of the population, it can be appreciated that the quantity of water used needlessly in a day's time is very great indeed. The excessive use of water involves, in many instances, increased costs to the consumer for electricity, water and sewer services and also puts an unnecessary burden on all sewage disposal systems.
When concerned people first came to realize this situation, it was not unusual for them to place bricks, rocks, or other water displacing articles in the flush tank to thereby reduce the volume of water available for a flush. It also came to be known to place weirs or dams in the flush tank surrounding the outlet valve, similarly for the purpose of reducing the volume of water in the tank available for flushing. Such constructions are disclosed in U.S. Pat. Nos. 3,259,918 and 3,731,324, which recite the common problems of securing and sealing the weirs or dams within the flush tank.
Another proposed solution is disclosed in U.S. Pat. No. 3,939,507 in which a cylindrical tube is placed atop the outlet to raise the minimum water level in the tank and thereby reduce the volume of water discharged during flushing. The cylindrical tube is intended to be a permanent arrangement similar to the weirs or dams previously discussed.
Also known to the applicant are the U.S. Pat. Nos. 2,760,206 and 3,916,455 each of which discloses a double valve construction, one atop the other, for selectively providing either a full flush or a partial flush, as desired.
In many instances, the prior art has disclosed complex constructions which are expensive to manufacture and maintain and which are not readily applicable to existing flush tanks. In many instances, they did not provide adjustments for selectively enabling a full flush or a partial flush. For example, in the earlier groups of patents or prior art described above, the expedients often only permitted a partial flush even when a full flush may have been desirable or necessary, as with solid wastes. Then, with respect to Patent No. 3,916,455 mentioned above, no mechanism was provided to automatically hold open the full flush valve until such time that a full flush was actually achieved. Rather, the operator was usually required to hold the operating handle in an extreme position until the full flush was obtained, else the full flush valve would close before the flush tank was completely emptied. Further, with respect to Patent No. 2,760,206, the flow rate permitted by the upper valve was significally less than that permitted by the lower valve, the result being a weak partial flush as compared with the full flush.